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19 Cards in this Set

  • Front
  • Back
Respiratory failure is described as either...
lung failure = hypoxemic: inadequate O2 delivery

pump failure = hypercapnic - respiratory acidosis
1. Decreased PinspO2
2. Decreased aveolar ventilation (V(A))
3. VQ mismatch
4. R-->L shunt
5. Diffusion limitation

... all are ____ causes of ______ failure.
physiological causes of hypoxemic failure.
Decreased V(A) ___ P(A)CO2 and ____ P(A)O2
increases PaCO2, and decreases PaO2.
Will a VQ mismatch respond to supplemental O2? Shunt?

Dead space?

no direct O2 effects, but the cytokine storm associated with causes of dead space might be causing 2ndary VQ mismatch, which would mean there would be 2ndary effects of O2.
What causes a shunt?
Respiratory distress syndrome, etc --> Stuff that fills the lungs with fluild, etc.
Does hypoxemia need to be fixed right away? Yes. How can this kill you?
Yes, b/c it can precipitate death.

Cardiac arrhythmias.
What is the ventilatory requirement equation?
V(A) = V(E) - V(D)
V(A) = V(E) x (1 - V(D) / V(T))

V(E): minute ventilation = respiratory rate x tidal volume
What is the CO2 balance equation?

This that elevate PaCO2 cause what kind of failure?
P(a)CO2 = 863 x VCO2 / V(A)

VCO2 = production of CO2 in liters per min.

Hypercapnic failure
3 Factors can cause hypercapnic respiratory failure?
Increased V(E) secondary to ^^VCO2
- fever, trauma, etc.

Increased V(E) secondary to ^^V(D)/V(T)
- pulmonary embolism, emphysema, etc.

Decreased V(E) --> Decreased V(A)
Decreased respiratory drive
Decreased Nerve conduction
Neuromuscular problems
chest wall issues
lung dz (asthma, COPD)
upper airway obstruction
...all can do what to V(E)?
Decrease it --> decrease V(A)
What are normal lvls for pH, pCO2, and HCO3-?

In acute failure?
compesated failure?
acute/chronic failure?
7.4, 40, and 24.

acidotic, ^pCO2, slliiiiightly up/normal HCO3-

sllllightly acidotic, ^pCO2, ^HCO3-

very acidotic (~7.25, etc); ^^pCO2 (~85), ^^HCO3- (~36)
A pt's respiratory drive can be taken over by O2 receptors (norm is CO2 receptors) if they have severe, long-term elevation of pCO2 --> desensitization.
- seen in what dz? Result?

Take home point:
- should you rely on hypoxemic respiratory drive in *acute* situations to keep your pts alive while you figure out the problem?

Acute effects?
Chronic effects?
some severe COPD
- they'll do better on 3/4ths of a liter of O2 as opposed to 1L of O2.


MIs, dysrhythmias
Organ damage.
Myasthenia gravis
- all can cause..?

Major one? time till onset?

Is hypercapnia an early or late sign of respiratory failure due to neuromuscular limitations?

What are clinical signs of respiratory muscle weakness? (4)
respiratory muscle weakness --> req ventilation

Deconditioning, can manifest in as short as 1wk of bedrest.

Must give support ventilation prior to respiratory failure.

decreasing VC
decreasing max inspir force
***ineffective cough***
What is the determining value for tracheal intubation?

Do respiratory stimulants help tx hypercapnic failure?
low pH

meh, they're pretty crummy.
What does Naloxone do?
reverses action of narcotics --> respiratory stimulant.
What are the two types of negative pressure assist devices?

what does CPAP stand for?

Iron lung, Cuirass ventilator

Continuous positive airway pressure

Cycled CPAP; bilevel positive airway pressure.
When are negative pressure devices best used (acute/chronic?)

When are CPAPs used?

BiPAP advantage over tracheal ventilation?
chronic setting.

in those w/ obstructive sleep apnea.

no/less risk of VAP.
What is PEEP?
- mechanism?
- functions? (2)
- adverse effects?
Positive end expiratory pressure
- sets expiratory pressure and ^^FRC, recruits aveoli that would otherwise collapse
- reduces airway and aveolar collapse; increases PaO2. when we can't do it enough with supplemental O2.
- barotrauma, decreased venous return, decreased CO
What should be treated first?